Cestode and Trematode lab

Diphyllobothrium latum

Fish tapeworm

Taenia saginata

Beef tapeworm

Taenia solium

Pork Tapeworm

Taenia pisiformis

Common dog/rabbit tapeworm

Echinococcus granulosa

Dog tapeworm

Echinococcus multilocularis

Dog/Fox tapeworm

Dipylidium canium

Double Pored/Flea tapeworm

Vampirolepis (Hymenolepis) nana

Dwarf Tapeworm

Hymenolepis diminuta

Dwarf Tapeworm

Diphyllobothrium latum lifecycle

1. Unembryonated eggs passed in feces

2. Eggs embryonate in water

3. Coracidia hatch from eggs; ingested by crustaceans

4. Grow to procercoid larvae

5. Infected crusaceans eaten by small fish; develop into pierocercoid larva

6. predator fish eats smaller fish

7. Human ingests raw or undercooked infected fish

What is the diagnostic stage of Diphyllobothrium latum?

Egg stage

What stage is the infective stage for Diphyllobothrium latum?

Pierocercoid larva

Taenid (Beef/Pork/Dog Tapeworms) Lifecycle

1. Eggs or gravid proglottids in feces or environment

2. Cattle/Pigs ingest contaminated vegetation

3. Oncospores hatch, penetrate intestinal wall, circulate to muscle

4. Oncospheres develop into cysticerci in muscle

5. Human ingests raw or undercooked infected meat

6. Scolex attach to intestine

7. Adults migrate to small intestine

What is the diagnostic stage for Beef/Pork/Dog tapeworms

Egg or Gravid Proglottid stage

What is the infective stage for Beef/Pork/Dog tapeworms

When the Oncospheres develop into cysticerci in muscle

What egg is this?

Diphyllobothrium latum egg

What egg is this?

Taeniid eggs

Echinococcus granulosus life cycle in Definitive host

1. adult in small intestine

2. Embryonated eggs in feces

3. Oncosphere hatches: penetrates intestinal wall

4. Hydatid cyst in various organs

5. Protoscolex from cyst

6. scolex attaches to intestine

Echinococcus multilocularis (alveolar) life cycle

1. Adult in small intestine

2. Embryonated egg in feces

3. Oncosphere hatches, penetrates intestinal wall

4. Alveolar hydatid cyst in visceral organs

5. Protoscolex from cyst

6. Scolex attaches to intestine

Echinococcus granulosus life cycle in humans

1. adult in small intestine

2. Embryonated eggs ingested

3. Oncospheres released in small intestine

4. Hydatid cysts in various organs

Echinococcus multilocularis (alveolar) life cycle in humans

1. Adult in small intestine

2. Embryonated egg ingested

3. oncospheres released in small intestine

4. alveolar hydatid cysts in liver; may disseminate to other organs

Dipylidium canium life cycle

1. Gravid proglottids passed intact in feces

2. Proglottids disintegrate and release egg packets

3. Flea larvae ingest egg packets. Oncospheres hatch; develop into cysticercoids

4. Flea larvae mature; harbor inefective cysticercoids

5. Definitive host ingests infected fleas (dogs/cats)

6. scolex

7. incidental transmission to humans

Infective stage of Echinococcus granulosus (cystic)

Embryonated egg in feces

Diagnostic stage of Echinococcus granulosos (cystic)

Hydatid cyst in various organs

Infective stage of Echinococcus multilocularis (alveolar)

Embryonated egg in feces

Diagnostic stage of Echinococcus multilocularis (alveolar)

Alveolar hydatid cyst in visceral organs (usually liver)

Infective stage of Dipylidium canium

When definitive host consumes fleas with cysticercoids

Diagnostic stage of Dipylidium canium

Gravid proglottids passed in feces and the release of egg packets

What eggs are these?

Dipylidium canium egg

Vampirolepis (Hymenolepis) nana lifecycle

1. embryonated egg in feces

2. Egg ingested by insect

3. cysticercoid develops in insect

4. Humans/rodents ingest cysticercoid infected arthropods

   1. Embryonated egg ingested by humans from contaminated food, water, or hands

5. oncosphere hatches, cysticercoid develops in intestinal villus

6. scolex

7. adult in illium

8. eggs released through genital atrium of gravid proglottids

   1. Gravid proglottids disintegrate, releasing eggs passed in stool

9. Autoinfection occurs if eggs remain in intestine

Infective stage of Vampirolepis (Hymenolepis) nana

Embryonated egg in feces

Diagnostic stage of Vampirolepis (Hymenolepis) nana

Embryonated egg in feces (same as infective)

What eggs are these?

Vampirolepis (Hymenolepis) nana

Scolex

Cestode head

Found on Anterior side

Contains structures for attachment and locomotion

Rostellum

Protruding cone line structure on Scolex

Equipped with hooks for attachment

Bothrium

Shallow facets/grooves in the head of the tapeworm

Help with attachment

Proglottid

The individual “reproductive packet” on a tapeworm

Contains both male and female anatomy

Strobila

The portion of the body behind the Scolex

Contains the proglottids

Monozoic

A primitive taxa lacking strobila

Body is a single unit

Polyzoic

When the body is comprised of a chain of proglottids (strobila)

Suckers

Cup shaped muscular structured used for attachment

Tegument

External body surface

What two systems are absent from Cestodes?

Digestive and Vascular

What is used to absorb food in Cestodes?

Tegument

Monoecius

Where both male and female reproductive systems exist

Protandrous

Where male reproductive organs are developed prior to female reproductive organs

Operculum

Lid like cover on some egg species

Oncosphere

First motile stage of larva

Hexacanth

Oncosphere with 3 pairs of hook structures

Cysticercoid

Second larval stage in some cestodes (H. diminuta, V. nana, D. canium)

Hydatid cyst

Vesicular structure formed in host tissue in which new scolices are formed (E. granulosus and E. multilocularis)

Coracidium

Ciliated hexacanth of D. latum

Procercoid

Second stage of D. latum in 1st intermediate host

Plerocericoid

D. latum stage reached in second intermediate host

Cysticerus

Second stage larvae in some cestodes (Taenia sp.)

Blood Flukes

Schistosoma mansoni

Schistosoma haematobium

Schistosoma japonicum

Common liver fluke

Fasciola hepatica/gigantica

Giant intestinal Fluke

Fasciolopsis buski

Oriental Lung Fluke

Paragonimus westermani/kellicotti

Chinese/Oriental Liver Fluke

Clonorchis sinensis

Schistosoma sps. Life Cycle

1. Eggs shed from infected humans (in feces and urine)

2. Eggs hatch and release miracidia

3. Miracidia penetrate snail tissue

4. Sporocysts develop in snail

5. Free swimming cercariae released into water

6. Cercariae penetrate skin

   1. Cercariae lose tails, becoming schistomulae

7. Circulation

8. Migration to blood portal in liver where maturation occurs

9. Paired adult worms migrate to either mesenteric venules of bowl OR venous plexus of bladder

What is the infective stage for Schistosoma spp.

Free-swimming cercariae

What is the diagnostic stage for Schistosoma spp.

Eggs shed from infected humans

What egg is this?

Schistosoma haematobium eggs

What egg is this?

Schistosoma japonicum egg

What egg is this?

Schistosoma mansoni egg

Fasciola hepatica/gigantica life cycle

1. Unembryonated eggs passed in feces

2. Eggs become embryonated in water

3. Miracidia hatch, seek out snails

4. Miracidia penetrate snail; develop from sporocysts into cercariae

5. Free-swimming cercariae encyst aquatic vegitation

6. Metacercariae ingested by definitive host

7. Immature flukes encyst in duodenum; migrate through liver parenchyma to billiary ducts

8. Adult flukes mature in hepatic billiary ducts

Infective stage of Fasciola hepatica/gigantica

Metacercariae on vegetation

Diagnostic stage of Fasciola hepatica/gigantica

Unembryonated eggs passed in feces

What egg is this?

Fasciola hepatica/gigantica egg

Fasciolopsis buski life cycle

1. unembryonated eggs passed in feces

2. Eggs embryonate in water

3. Miracidia hatch, penetrate snail

4. Develop from sporocysts into cercariae

5. Free-swimming cercariae

6. Metacercariae on water plant ingested by humans or pigs

7. encyst in duodenum

8. adults in small intestine

What is the infective stage of Fasciolopsis buski

Metacercariae on water plant

What is the diagnostic stage of Fasciolopsis buski

unembryonated eggs in feces

Paragonimus westermani/kellicotti life cycle

1. unembryonated eggs

2. become embryonated in water

3. Miracidia hatch; penetrate snail

4. Sporocysts debelop into cercariae

5. Cercariae invade crustaceans; encyst into metacercariae

6. Humans ingest inadequately cooked or pickled crustaceans with metacercariae

7. Metacercariae encyst in duodenum

8. Adults in cystic cavities in lungs

Diagnostic stage of Paragonimus westermani/kellicotti

Unembryonated eggs

Infective stage of Paragonimus westermani/kellicotti

Metacercariae in crustaceans

What egg is this?

Paragonimus westermani egg

Clonorchis sinensis life cycle

1. embryonated eggs passed in feces

2. Eggs ingested by snail

   1. Develop from miracidia to cercariae

3. Free-swimming cercariae encyst in skin or flesh of fresh water fish

4. Infected fish eated by human

5. Encyst in duodenum

6. Adults in biliary duct

Diagnostic stage of Clonorchis sinensis

Embryonated eggs in feces

Infective stage of Clonorchis sinensisi

Infected fish is consumed

What egg is this?

Clonorchis sinensis egg

Endoparasite

A parasite that lives within another organism

Cercaria (Cercariae)

Trematode larva

Develops from a sporocyst or a redia

Daughter Sporocyst

Larval stage in certain trematodes

Reproduces asexually

Dioecious

Containing both male and female reproductive organs

Distome

Largest trematode group

Anterior and Oral sucker on ventral portion of body

Monostome

Only has the oral sucker, located on anterior

Gastrome